Comparsion of Pd-based Controllers for Robotic Manipulators

PD control is widely used in industrial robotic manipulators because of its simple structure and acceptable performance. In this paper, the PD-based control schemes for the trajectory tracking of the robotic manipulators are addressed. The fixed gain PD control, the nonlinear gain PD (NPD) control, the adaptive PD learning control (PD-LC), and the adaptive NPD learning control (NPD-LC) are applied for the trajectory tracking of both serial and parallel robotic manipulators. The PD-LC and NPD-LC controllers can be used to improve the tracking performance for the repeatable tracking tasks in an iterative mode. The PD-LC and NPD-LC consists of a PD/NPD control as the basic feedback control and an additional feedforward control term directly inherited from the previous iteration of the same control task. A comparative study of four PD-based controllers is conducted to understand how different control schemes will affect the trajectory tracking performance, and the results are shown in this paper. Case studies are presented to demonstrate the validity of the PD-LC and NPD-LC algorithms.